Issue 4488 - Add support for JSON page front matter

tests/test_site/pages/sitemap.tmpl

 product = foo
 title = test_metadata
 tags = [popular, bar]
 <h1> Unfiltered </h1>
 <ul>
-{%- for unfiltered_page in get_pages_metadata()|sort %}
+{%- for unfiltered_page in get_pages_metadata()|sort(attribute='page') %}

[Sebastian Noack, 2018/04/18 21:12:27]

Nit: The changes here seem unrelated now. Still it makes sense to sort by
"page", otherwise the order is somewhat arbitrary. Either way this makes sense
regardless of this change, and therefore could be committed separately.

[rosie, 2018/04/18 22:46:18]

Is there any advantage to committing it separately? Is it more transparent, or
easier to track changes that way? If so, then no problem, this can be a separate
commit.

[Sebastian Noack, 2018/04/19 00:22:25]

If this change is unrelated, i.e. can be separated from the main change this
review is about, and both changes still have the intended effect without
breaking anything if applied individually, then the advantages are:

1. If we ever decide to revert either change, doing so is trivial.
2. When somebody comes across this change in the future, who hasn't been part of
this discussion, unrelated changes cause confusion.
3. During code review its more efficient and effective if reviewers don't have
to focus on more things than necessary at the same time.

[rosie, 2018/04/19 03:31:01]

Sounds good. Done.

   <li>title : {{ unfiltered_page['page']}} </li>
 {%- endfor %}
 </ul>
 
 <h1> Filtered </h1>
 <ul>
-    {%- for filtered_page in get_pages_metadata({'tags': ['popular', 'bar']})|sort -%}
+    {%- for filtered_page in get_pages_metadata({'tags': ['popular', 'bar']})|sort(attribute='page') -%}
         <li>title : {{ filtered_page['page'] }} </li>
 {%- endfor %}
 </ul>
 
 <h1> String Filter For Listy Option </h1>
 <ul>
-    {%- for filtered_page in get_pages_metadata({'tags': 'popular'})|sort -%}
+    {%- for filtered_page in get_pages_metadata({'tags': 'popular'})|sort(attribute='page') -%}
         <li>title : {{ filtered_page['page'] }} </li>
 {%- endfor %}
 </ul>